Determination of metallo-organic species in lubricating oil by electrothermal vaporization inductively coupled plasma mass spectrometry

Inductively coupled plasma mass spectrometry (ICP-MS) is one of the few techniques capable of multielement determinations with low detection limits. However, when an organic matrix is nebulized into the ICP-MS, carbon condenses on the cooled interface cones, sooting and blocking the apertures. A second disadvantage of nebulizing organics into the ICP-MS is that carbide compounds formed in the ICP may act as molecular interferences for some elements, making it difficult or impossible to detect these elements. Electrothermal vaporization (ETV) was chosen as a sample introduction technique because it reduced the problems associated with conventional nebulization. When using ETV for sample introduction, the analyte was separated from the sample matrix, which made it possible to analyze oil samples while eliminating oxygen addition and reducing molecular interferences due to the organic matrix. We have developed a method for the determination of Al, Mg, Fe, and Y metallo-organic compounds in lubricating oil by electrothermal vaporization inductively coupled plasma mass spectrometry. A pneumatically-operated graphite plug holder was added to the ETV so that the dosing hole could be plugged during the ETV heating cycle.